Mercury-vapor spark gap



Dec. 15, I P. THOMAS MERCURY VAPOR SPARK GAP Filed Aug. 18, 1921 r 4 g J- -f}+ l g r ::-:ffi, Y 26 /VVITNESSES: INVENTOR Mr Phi/0 6 Thomas ATTORNEY Patented Dec. 15, 1925.

UNITED STATES "PATENT OFFICE.

PHILLIPS THOMAS, OF EDGEWOOD, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

MERCURY-VAPOR SPARK GAP.

Application filed August is, 1921. Serial No. 493,491.

To aZZ whom it may concern:

Be it known that I, PHILLIPS THOMAS, a citizen of the United States, and a resident of Edgewood, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Mercury- Vapor Spark Gaps, of which. the following is a specification.

My invention relates to electrical apparatus and more especially to spark-gap devices.

The object of my invention is to provide an improved structure for such spark gaps as involve the use of a metallic vapor.

When spark gaps of the mercury-vapor type, as heretofore constructed, are operated continuously for long periods of time, there is a marked tendency for the mercury vapor, upon condensation, to return more to one of the liquid electrodes or pools than to the other. The transfer of the mercury from one pool to the other is cumulative by reason of the excessive heating in the pool which does not have its full share of mercury. The ultimate result is a decrease in the area of the smaller pool to such proportions that the spark gap ceases to operate.

According to my invention, I provide a gap structure of such design as to obviate the above-mentioned difliculties. In my structure, as will be hereinafter explained, the mercury vapor, upon condensation, is caused to return to the pool from which it originated.

The gap structure embodying my invention comprises apair of parallel disposed tubular members, opposite portions thereof serving as containers for liquid electrodes and as condensing chambers, and a connecting member between said tubes having a centrally elevated portion, said connecting member connecting such portions of said tubular members as to admit of an arc current flow between said liquid electrodes.

Other objects of my invention, as well as details of construction, whereby my invention may be practiced, will be apparent from the following description and accompanying drawing, wherein:

The single figure is a diagrammatic view of circuits and apparatus embodying my invention.

In the drawing, is shown a mercury-vapor spark-gap apparatus 1 disposed in a chamber 2 which contains a cooling liquid 3, such, for

example, as oil. The spark gap 1 comprises a pair of vertically disposed tubularmemhers 4.- and 5, the upper ends 6 and 7 serving as condensing chambers and the lower ends i and 9 serving as receptacles for mercury electrodes 11 and 12, respectively. tubular member 13 having a centrally elevated point 14, serves to connect the tubular members 4 and 5 at points adjacent the'upper surfaces of the pools to admit of an arc current flow between the liquid electrodes 11 and 12.

The are between the liquid electrodes 11 and 12 may be started by any of the usual methods, such, for example,as by tilting the spark gap, by a static discharge or by an auxiliary or tickler electrode. In the drawing, I have shown one arrangement for starting the arc according to the first method. The tilting arrangement may also be used to control the arc length by maintaining the tube in an inclined position. The spark-gap device 1 may be pivotally mounted upon a supporting member 15, which is shown as secured to the base of the chamber 2, and be tilted by means of a rod 16 which is pivotally connected to 2. lug 17 that is rigidly secured to the tubular connecting member 13. Conductors 18 and 19 are sealed into the walls of the portions 8 and 9 of the tubes t and 5, respectively, to serve as circuit terminals for the liquid electrodes 11 and 12.

For purposes of illustration, I show the spark-gap device embodying my invention as serving in a high-frequency inductioniurnace circuit. The circuit is energized from an alternating-current generator 21 through a step-up transformer 22 and comprises the spark-gap device 1, an inductive furnace 23 and a condenser 24, opposite terminals of the latter being connected to the high-tension leads 25 and 26 'of the transformer 22. The induction furnace 23 comprises a crucible 27, containing a material 28, and a coil 29 which is so disposed as to cause the heating of the material 28 by means of high-frequency currents induced by the coil 29.

In operation, upon striking an arc be-- known principles, and, in order to simplify the description o1" my invention, will not be further explained.

While I have shown a specific embodiment of my invention, 1 do not Wish to be limited thereto, but I desire that only such limitations shall be imposed upon my invention, as are indicated in the prior art or as are specifically set forth in the appended claims.

I claim as my invention:

1. in a spark-gap device, an H-shaped container, the two upright portions constituting distinct chambers, a vaporizable electrode at the lower end of each chamber, the cross connection being a tube connecting said chambers and affording a space-current path, the portions of each chamber above the cross connection constituting condensing chambers and having a greater cooling surface than said cross connection.

2. In a spark-gap device, an H-shaped container, the two upright portions constituting distinct chambers, a vaporizable electrode at the lower end of each chamber, the cross connection being a tube connecting said chambers and affording a space-current path, the central portion of said tube being sufficiently elevated to prevent condensate flowing from one chamber to the other, the

portions of each chamber above the cross connection constituting condensing chambers and having a greater cooling surface than said cross connection.

In a high-frequency circuit, a spark gap comprising an H-shaped vessel in a cooling medium, the cross-arm of the H being shorter than either of the arms connected thereby and the portions of said arms below said cross-arm being each filled with mercury to a depth approximately equal .to the length of said cross-arm and electrical connections whereby said mercury constitutes the electrodes of said spark gap.

In a high-frequency circuit, a spark g p comprising an H-shaped vessel in a coolmedium, the cross-arm of the H being shorter than either of the arms connected thereby, the portions of said arms above said cross-arm being greater than said cross-arm and the portions of said arms below said cross-arm being each filled with mercury to a depth approximately equal to the length of said cross-arm and electrical connections whereby said mercury constitutes the electrodes of said spark gap.

In testimony whereof, I have hereunto subscribed my name this 16th day of August,

PHILLIPS THOMAS. 

